Connect via Bluetooth with Delphi XE7 using portable printer

Question

I\'m trying to communicate with a Sewoo LK-P32 printer via Bluetooth. For this, I am using Delphi XE7. I made a few examples that come with Del

Answer 1

In your loop, you keep assigning to lDevice. If there is a second unpaired device then lDevice is pointing to that. You need top Exit once you have detected that it is paired.

Also, I personally don't like raising exceptions deliberately. If a class instance is nil then you should exit, nolt drill down into it..

For instance

if FBluetoothManager = nil then
begin
  Memo1.Lines.Add('FBluetoothManager esta nulo');
  Exit;
end;

Answer 2

I recreated your program, and i get the same problem, but changing your code, it's working fine for me now.

The problem is here

if FSocket <> nil then
begin
  // FSocket.Connect;
  FSocket.Connect;
  Memo1.Lines.Add('Criou socket cliente com o ServerSocket');
  Texto := #27 + '|cA' + 'Teste' + #13#10;
  ToSend := TEncoding.UTF8.GetBytes(Texto);
  FSocket.SendData(ToSend);
  Memo1.Lines.Add('Enviou ' + Texto + ' para a impressora.');
end

First, i recommend to add Fsocket as a private property, and create ONLY ONE fsocket object. So, your code will changed to

if (Assigned(LDevice)) And (Assigned(FSocket))
then Begin
     if Not FSocket.Connected
     then FSocket.Connect
     End
Else Begin
     FSocket := LDevice.CreateClientSocket(Guid, True);
     Memo1.Lines.Add('Device Socked created to '+LDevice.DeviceName);
     FSocket.Connect;
     End;

After connected, you can call a TTimer to send what you want, o create a method checking if Fsocket is connected.

if Assigned(FSocket)
then Begin
     if FSocket.Connected
     then Begin
          Texto := #27 + '|cA' + 'Teste' + #13#10;
          ToSend := TEncoding.UTF8.GetBytes(Texto);
          FSocket.SendData(ToSend);

          Sleep(100);
          End;
     End;

Also, you can add a sleep between 2 commands, to be sure the data are received and executed by your printer.

In my case i used an Arduino width Bluetooth hc-06 module.